This application is based on Japanese Patent Application Nos. 2001-338296 filed Nov. 2, 2001 and 2002-081957 filed Mar. 22, 2002, the contents of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to an optical fiber connecting element, an optical alignment sleeve, an optical fiber connecting method, and an optical fiber connecting device, and more specifically, to a method of fixedly connecting an optical fiber using an optical alignment sleeve filled with an adhesive.
2. Description of the Related Art
In laying an optical fiber cable, for example, a cable of unit length 2 km is laid in each section. Cables in two sections are connected together by connecting optical fibers in the cable in one of the sections to the corresponding optical fibers in the cable in the other section using a connection box called a xe2x80x9cclosurexe2x80x9d. A cable for long-distance transmissions requires a large number of closures, and a multicore cable requires optical fibers to be connected together a huge number of times. Accordingly, it is necessary to be able to connect optical fibers together more precisely and to reduce the number of times that the optical fibers are connected together, thereby achieving inexpensive and reliably durable optical-fiber connections.
Conventionally known methods of connecting optical fibers together include (1) heating and melting the optical fibers, i.e. so-called fusion splicing, (2) mechanically fixing the optical fibers in a connection box, i.e. so-called mechanical splicing, and (3) using transparent sleeves or V-type grooves with transparent covers to butt the optical fibers against each other and using an UV-curable adhesive to fixedly connect the optical fibers together, i.e. so-called adhesive splicing.
However, the fusion splicing requires an expensive fusion splicer, which is large and does not allow connections to be carried out easily in a narrow area. Another problem with the fusion splicing is that the optical fibers require an extra length sufficient to allow the fibers to be set in the fusion splicer and an extra length for a reconnection carried out if the fusion fails.
The mechanical splicing requires more inexpensive connection tools than the fusion splicing but requires an expensive connection element, a mechanical splice container, thereby increasing costs per connection. Another problem with the mechanical splicing is that the fixation of the optical fibers rely on mechanical clamping force, thereby degrading durability reliability.
Problems with the adhesive splicing are that UV irradiation, which involves high costs, are required and that ultraviolet rays are harmful to human bodies, resulting in degraded operability at the working site.
It is an object of the present invention to provide an optical alignment sleeve and an optical fiber connecting element that enable quick, easy, and inexpensive connections even in a narrow area, thereby achieving high operability and high durability reliability, and to provide an optical fiber connecting method and apparatus used for the optical alignment sleeve and the optical fiber connecting element.
To attain this object, an optical fiber connecting element comprises an optical alignment sleeve having tapered insertion ports formed at opposite ends thereof and through which optical fibers are inserted and having an ejection port opened in an area in which the two optical fibers inserted through the insertion ports are butted against each other, a cyanoacrylate-type glue injected into the insertion ports and the injection port to fix the two optical fibers, and a heat-shrinkable tube wrapped around the optical alignment sleeve and the two optical fibers and having a hot-melt adhesive provided therein.
Also an optical fiber connecting element may comprise an optical alignment sleeve having tapered insertion ports formed at opposite ends thereof and through which optical fibers are inserted and having an ejection port opened in an area in which the two optical fibers inserted through the insertion ports are butted against each other, a cyanoacrylate-type glue injected into the insertion ports and the injection port to fix the two optical fibers, a reinforcing tube wrapped around the optical alignment sleeve and the two optical fibers, and seal materials that fix the two optical fibers and the reinforcing tube at opposite ends of the reinforcing tube.
Further, an optical fiber connecting method comprises a first step of inserting two optical fibers into an optical alignment sleeve and butting the optical fibers against each other, the optical alignment sleeve having tapered insertion ports formed at opposite ends thereof and through which optical fibers are inserted and having an ejection port opened in an area in which the two optical fibers inserted through the insertion ports are butted against each other, a second step of injecting a cyanoacrylate-type adhesive into the insertion ports and the injection port to fix the two optical fibers, and a third step of wrapping a heat-shrinkable tube having a hot-melt adhesive provided inside, around the optical alignment sleeve and the two optical fibers and heating the heat-shrinkable tube to fix the optical alignment sleeve and the two optical fibers.
Furthermore, an optical fiber connecting method may comprise the steps of: inserting two optical fibers into an optical alignment sleeve and butting the optical fibers against each other, the optical alignment sleeve having tapered insertion ports formed at opposite ends thereof and through which optical fibers are inserted and having an ejection port opened in an area in which the two optical fibers inserted through the insertion ports are butted against each other, injecting a cyanoacrylate-type adhesive into the insertion ports and the injection port to fix the two optical fibers, and wrapping a reinforcing tube around the optical alignment sleeve and the two optical fibers and using seal materials to fix the two optical fibers at opposite ends of the reinforcing tube.
An optical alignment sleeve for optical fibers which allows two optical fibers to be butted against each other for connection, the optical alignment sleeve comprises tapered insertion ports through which optical fibers are inserted, and holding sections each having a groove formed therein to allow the optical fiber inserted through the insertion port to discharge an extra portion of an adhesive already filled in the optical alignment sleeve, to the insertion ports, and wherein the optical fibers inserted through the insertion ports allow the extra portion of the adhesive discharged to the insertion ports to form fillets.
Also the optical alignment sleeve may comprise tapered insertion ports through which optical fibers are inserted, and holding sections each having a drain section formed therein so that the optical fiber are inserted through the insertion port to discharge an extra portion of an adhesive already filled in the optical alignment sleeve, to the insertion ports, and wherein the optical fibers are inserted through the insertion ports to allow the extra portion of the adhesive discharged to the insertion ports to form fillets.
An optical fiber connecting method comprises a first step of inserting optical fibers into an optical alignment sleeve to discharge an extra portion of an adhesive already filled into holding sections of the optical alignment sleeve, to insertion ports formed at opposite ends of the optical alignment sleeve, via grooves formed in the holding sections, a second step of inserting the optical fibers into the optical alignment sleeve to allow the extra portion of the adhesive discharged to the tapered insertion ports to form fillets, and a third step of solidifying the adhesive to fix the optical alignment sleeve and the optical fibers.
Also an optical fiber connecting method comprise a first step of inserting optical fibers into an optical alignment sleeve to discharge an extra portion of an adhesive already filled into holding sections of the optical alignment sleeve, to insertion ports formed at opposite ends of the optical alignment sleeve, via grooves formed in the holding sections, a second step of inserting the optical fibers into the optical alignment sleeve to allow the extra portion of the adhesive discharged to the tapered insertion ports to form fillets, and a third step of solidifying the adhesive to fix the optical alignment sleeve and the optical fibers.
An optical fiber connecting device comprises optical alignment sleeve holding means for fixing an optical alignment sleeve, and optical fiber holding means having a clamp that fixes optical fibers in V-type groove and means for moving the clamp so as to allow the optical fibers to be inserted into the optical alignment sleeve and butted against each other therein, and wherein the clamp has a fixed cover that can be closed with the optical fibers temporarily fixed in the V-type groove formed in a clamp base, using one of the fingers, and the optical fibers are sandwiched between the clam base and the fixed cover in the V-type groove.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.